Exact Kahler Potential from Gauge Theory and Mirror Symmetry
Jaume Gomis, Sungjay Lee
TL;DR
This work proves that the exact partition function on the two-sphere for ${ m N}=(2,2)$ theories flowing to Calabi–Yau sigma models encodes the exact Kahler potential on the quantum Kahler moduli space, i.e., $Z( au_a,ar{ au}_a)=e^{- ext{K}( au_a,ar{ au}_a)}$, and uses this to access worldsheet instanton data. It provides two complementary proofs: (i) a localization-based analysis on a squashed sphere showing $Z_b$ is $b$-independent and reduces to a Ramond-sector ground-state overlap in the degenerate limit, (ii) a Landau–Ginzburg mirror analysis showing $Z= extstyle extstylerac{}{}\
Abstract
We prove a recent conjecture that the partition function of N=(2, 2) gauge theories on the two-sphere which flow to Calabi-Yau sigma models in the infrared computes the exact Kahler potential on the quantum Kahler moduli space of the corresponding Calabi-Yau. This establishes the two-sphere partition function as a new method of computation of worldsheet instantons and Gromov-Witten invariants. We also calculate the exact two-sphere partition function for N=(2,2) Landau-Ginzburg models with an arbitrary twisted superpotential W. These results are used to demonstrate that arbitrary abelian gauge theories and their associated mirror Landau-Ginzburg models have identical two-sphere partition functions. We further show that the partition function of non-abelian gauge theories can be rewritten as the partition function of mirror Landau-Ginzburg models.
